Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content


workers, building, architect

NORA Manufacturing Sector Strategic Goals

9278428 - Birth Defects and Parental Occupational Exposures

Start Date: 10/1/2002
End Date: 9/30/2010

Principal Investigator (PI)
Name: Christina Lawson
Phone: 513-841-4171
Organization: NIOSH
Sub-Unit: DSHEFS
Funded By: NIOSH

Primary Goal Addressed

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

The purpose of this study is to provide detailed exposure assessment data for the National Birth Defects Prevention Study (NBDPS) that will allow for examination of the link between occupational exposures and birth defects. The project involves collaboration between NIOSH, the CDC National Center on Birth Defects and Developmental Disabilities and the eight state-based Centers that form the NBDPS. Industrial hygiene expertise and published measurement data are being used to assess exposure to several maternal occupational hazards based on information obtained from the mothers of cases and controls. Exposure data will then be analyzed to examine potential risks of certain birth defects. In addition, technical assistance is being provided concerning a cluster of birth defects.


The ongoing National Birth Defects Prevention Study (NBDPS), which began collecting data in 1997, is a population-based case-control study that covers an annual birth population of 482,000 and includes cases identified from birth defect surveillance registries in ten states (or centers). We are collaborating with the Centers for Disease Control and Prevention National Center on Birth Defects and Developmental Disabilities (NCBDDD) to conduct a detailed exposure assessment of maternal occupational exposure data, providing a unique and timely opportunity to analyze much needed data on occupational exposures and birth defects. In addition, we are providing technical assistance concerning a cluster of birth defects in a manufacturing plant in Minnesota.

The objectives of the study are as follows:

1) Use industrial hygiene expertise to assess exposure to chemicals from occupation, industry, and job description data;

2) Examine the link between parental occupation and risk of specific birth defects;

3) Build a system for assessing parental occupational exposure with relation to birth defects.

4) Evaluate the chemical exposures associated with the birth defect cluster in Minnesota.

These objectives contribute to the reproductive health program in IWSB and are in line with the mission of the NORA Reproductive Health Research Team, who identified the lack of information on parental occupational exposures and risks of birth defects as a primary data gap. Another goal of the reproductive health program is to improve NIOSH's response to requests to evaluate workplace adverse reproductive health clusters. By fostering a partnership with CDC/NCBDDD and by establishing a system for occupational exposure assessment using data from the National Birth Defects Prevention Study, we will improve our ability to respond to such issues as they arise.

Two different methods of exposure assessment are being used for assessing occupational exposures to 16 substances of interest. One method involves expert opinion from experienced industrial hygienists. This method will be conducted two times (by two different industrial hygienists) for each job, in order to assess reliability. A panel will then be convened to resolve disagreements. The other method of exposure assessment involves a thorough search of published measurement literature and building a database containing published data. The assessments are then based on knowledge and actual measurement data in addition to expert opinion. This method is used for those substances that have been well studied and that are likely to have a higher number of subjects exposed.

Among the CDC and NCI researcher constituents are some of the Nation's leading researchers in birth defects and exposure assessment. The results of this project will be used to generate multiple papers on various etiologic hypotheses, such as exposure to solvents, metals, and pesticides with several defect groups.

For the NBDPS: In FY08, a manuscript describing the reliability of the expert opinion method was drafted. Also in FY08, exposure metrics were created for pesticides and solvents. In FY09, we plan to complete cleaning and dissemination of exposure data to collaborators, and to submit the reliability manuscript.

For the cluster evaluation: In FY08, data collection began. In FY09, we plan to complete data collection and draft a final report to the company.


The objectives of this project are to: 1) expand research of parental occupational exposures on the risk of birth defects in offspring. This information will be useful in generating future hypotheses for further study. The information may also be helpful to men and women of reproductive age who work with certain chemicals. The results of this study will be shared with other scientists in the field through peer-reviewed scientific journals publications and presentations at national and international conferences, and; 2) to maximize the potential impact, the results will also be translated and communicated in the annual newsletter of the CDC's National Center on Birth Defects and Developmental Disabilities (NCBDDD) and on their website. We will work with the NCBDDD, other state and local health departments, and the March of Dimes to formulate appropriate recommendations to workers concerning exposure to chemicals.

Mission Relevance

A data gap identified by the NORA Reproductive Health Research Team is the lack of information on parental occupational exposures and risks of birth defects. The majority of the 84,000+ chemicals used in the workplace remain untested for reproductive effects. The human and economic toll of birth defects is significant; in the US, more than 120,000 infants are born each year with birth defects; accounting for more than 20% of all infant deaths in the US; and contribute substantially to childhood illnesses, lifelong disabilities and social challenges, resulting in high costs in human suffering and medical and non-medical costs. The estimated lifetime costs for 18 of the most clinically significant birth defects in the U.S. were 8 billion dollars in 1992 ($75,000 - $503,000/ new case).

A first step to preventing birth defects is to identify their causes. However, the causes are still unknown for approximately 70% of all birth defects. Until recently, there have been few high quality birth defect surveillance systems in the US; the few existing systems have little or no information on occupational exposures. NIOSH has received requests to evaluate birth defect clusters in the workplace, but the ability to respond to such requests has been limited because little is known about the link between occupational factors and congenital abnormalities. With the creation of a system for assessing occupational exposures, NIOSH will be better equipped to handle future requests.

This study will have a large impact on the field of occupational reproductive research. By combining the experience in occupational epidemiology of NIOSH investigators and the exposure assessment methods created by the National Cancer Institute with the knowledge of birth defects at CDC, and the surveillance capabilities at the state level, this project will create a system for exposure assessment that will be available for ongoing state and national surveillance.

Because the National Birth Defects Prevention Study is a population study, mothers of cases and controls were likely employed in almost all, if not all, idustries. We anticipate that many of the mothers were employed in the Services, Health Care and Social Assistance and Wholesale and Retail Trade sectors - the sectors employing the largest number of women.

Cross-Sector Programs: Cancer, Reproductive, and Cardiovascular Disease: Activity/Output Goal 3.1.2. (09PPCRCAOG3.1.2); Conduct studies of high-priority exposures to identify and quantify risk of adverse reproductive health associated with workplace exposures. Activity/Output Goal 3.1.5. (09PPCRCAOG3.1.5);Improve retrospective exposure assessment methods for use in case-control studies of adverse reproductive outcomes that are more rare, such as congenital anomalies. Other Cross-Sector Programss -Exposure Assessment: Intermediate Goal 2.3 (09PPEXAIG2.3): Develop and evaluate new or improved methods for assessing exposure to workplace chemicals and occupational health stressors either singly or as mixtures, including both prospective and retrospective methods. Activity/Output 2.3.1 (09PPEXAAOG2.3.1): Development of new or improved methods to measure chemicals or other occupational hazards in the work environment. Activity/Output 2.3.2 (09PPEXAAOG2.3.2): Validation of these methods to provide and characterize their performance (specificity, sensitivity, accuracy, etc.) including publication in the NIOSH Manual of Analytical Methods. Activity/Output 2.3.3 (09PPEXAAOG2.3.3): Application of these methods to evaluate occupational exposure.