PT - JOURNAL ARTICLE AU - Andrea ‘t Mannetje AU - Amanda Eng AU - Chris Walls AU - Evan Dryson AU - Manolis Kogevinas AU - Collin Brooks AU - Dave McLean AU - Soo Cheng AU - Allan H Smith AU - Neil Pearce TI - Sex ratio of the offspring of New Zealand phenoxy herbicide producers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin AID - 10.1136/oemed-2016-103771 DP - 2017 Jan 01 TA - Occupational and Environmental Medicine PG - 24--29 VI - 74 IP - 1 4099 - http://oem.bmj.com/content/74/1/24.short 4100 - http://oem.bmj.com/content/74/1/24.full SO - Occup Environ Med2017 Jan 01; 74 AB - Objectives Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has inconsistently been associated with a decreased sex ratio of the offspring (number of male births divided by total births). We conducted a study among men and women who were employed in a New Zealand phenoxy herbicide production plant between 1969 and 1984, to study their offspring sex ratio in relation to their back-calculated TCDD serum concentrations determined in 2007/2008.Methods A total of 127 men and 21 women reported that 355 children were conceived after starting employment at the plant. The association between their lipid-standardised TCDD serum concentrations back-calculated to the time of their offspring's birth and the probability of a male birth was estimated through logistic regression, adjusting for the age of the exposed parent at birth, current body mass index and smoking.Results The overall sex ratio was 0.55 (197 boys, 158 girls). For fathers with serum TCDD concentrations ≥20 pg/g lipid at time of birth, the sex ratio was 0.47 (OR 0.49; 95% CI 0.30 to 0.79). The probability of a male birth decreased with higher paternal serum TCDD at time of birth (<4; 4–20; 20–100; ≥100 pg/g lipid), with ORs of 1.00 (reference); 1.00 (95% CI 0.50 to 2.02); 0.52 (95% CI 0.29 to 0.92); 0.45 (95% CI 0.23 to 0.89), p trend 0.007. For exposed mothers, the sex ratio was not reduced.Conclusions This study indicates that paternal serum TCDD concentrations in excess of an estimated 20 pg/g lipid at time of conception are associated with a reduced sex ratio.